1. Field of the Invention
The present invention relates to a network status indicating circuit, and particularly to a network status indicating circuit compatible with different types of network ICs.
2. Description of Related Art
There are two types of network status indicating circuits for indicating network status: 1) a first type of network status indicating circuit indicates the network status according to the combination of two status signals designated Speed and Link, 2) a second type of network status indicating circuit indicates the network status according to two status signals independent from each other designated 10M/LINK/ACTIVITY and 100M/LINK/ACTIVITY. Referring to FIG. 2, the first type of network status indicating circuit includes a first type of network IC 10, an inverter U1, two LEDs D1, D2, and a resistor Ra. The network IC 10 includes a Speed pin connected to an anode of the LED D1 and an input terminal of the inverter U1. An output terminal of the inverter U1 is connected to an anode of the LED D2. A node A between two cathodes of the two LEDs D1, D2 is connected to a Link pin of the network IC 10 through the resistor Ra. The inverter U1, the two LEDs D1, D2 and the resistor Ra constitute an indicator circuit. The network IC 10 is set in a kernel board, and the indicator circuit is set in a device board.
Level/value of the Link pin corresponding to the network status, and level/value of the Speed pin corresponding to the network transmitting speed are listed as below:
TABLE 1Network statusLevel/value of Link pinLinkedLow/0Not linkedHigh/1Transmitting and ReceivingAlternating between 0, 1
TABLE 2Network transmitting speedLevel/value of Speed pin 10 MbpsHigh/1100 MbpsLow/0According to Table 1, value at the Link pin is 0 when the network is “linked”, and is 1 when the network is “not linked”. When the network is “transmitting and receiving”, the value at the Link pin alternates between 0 and 1. According to Table 2, the value at the Speed pin is 1 when the speed of the network is 10 Mbps, and is 0 when the speed of the network is 100 Mbps. So when the network speed is 10 Mbps and the network is “linked”, the LED D1 lights up. When the network speed is 100 Mbps and the network is “linked”, the LED D2 lights up. When the network speed is 10 Mbps and the network is “transmitting and receiving”, the LED D1 blinks. When the network speed is 100 Mbps and the network is “transmitting and receiving”, the LED D2 blinks. When the network is “not linked”, the two LEDs D1 and D2 remain off.
Referring to FIG. 3, the second type of network status indicating circuit includes a second type of network IC 30, two resistors Rb, Rc, and two LEDs D3, D4. A 10M/LINK/ACTIVITY pin of the network IC 30 is connected to an anode of the LED D3 through the resistor Rb, and a 100M/LINK/ACTIVITY pin of the network IC 30 is connected to an anode of the LED D4 through the resistor Rc. Cathodes of the two LEDs D3 and D4 are grounded. The two resistors Rb and Rc, the two LEDs D3 and D4 constitute an indicator circuit. The network IC 30 is set in a kernel board, and the indicator circuit is set in a device board. When the network speed is 10 Mbps and the network is “linked”, the LED D3 lights up. When the network speed is 10 Mbps and the network is “linked”, the LED D4 lights up. When the network speed is 10 Mbps and the network is “transmitting and receiving”, the LED D3 blinks. When the network speed is 100 Mbps and the network is “transmitting and receiving”, the LED D4 blinks. When the network is “not linked”, the two LEDs D3, D4 remain off.
According to the FIGS. 2 and 3, an indicator circuit is only compatible with a specified network IC, so different indicator circuits are needed corresponding to different network ICs. Sometimes the network IC in the kernel board must be changed, and the indicator circuit in the device board must also be changed in accordance with the network IC. However, when specifications of customer orders for the kernel boards change, and current device boards on hand are not compatible with the new order, the device board has to be redesigned and tested, which increases costs and wastes time.
What is needed, therefore, is a network status indicating circuit comprising an indicator circuit compatible with different types of network ICs.